Conventional armored motor vehicles attempt to moderate the effect of mines and explosive devices by using armor of a thickness that will not be penetrated by penatrators, soil, rocks or the like, or by the blast from such a mine or explosive device. Such vehicles generally have bottom surfaces parallel to the surface on which they ride, side surfaces perpendicular to the surface on which they ride and relatively low ground clearance. In addition, front and rear wheel wells, front and rear drive assemblies, and front and rear wheels are typically positioned with respect to the vehicle body in substantially the same location as on a non-armored motor vehicle.
When such vehicles detonate an anti-vehicle mine below the vehicle, a penetrator and/or debris above the mine are propelled upward. If the vehicle has a relatively low ground clearance it confines the energy from the explosive blast beneath the vehicle and, as a result, the energy from the mine blast is efficiently transferred to the bottom of the vehicle. This can result in the mine defeating the armor and allowing the penetrator, debris or the blast energy to breach the armor and enter the vehicle. If the bottom of the vehicle is higher above the surface on which the vehicle runs (i.e., the vehicle has a higher ground clearance) more of the blast energy could dissipate in the space above the ground before encountering the bottom of the vehicle. A large ground clearance significantly reduces the amount of energy impinging on the bottom of the vehicle and reduces the efficiency of energy being transferred to the vehicle at locations distant from the detonation point of the mine.
In addition, some portion of the blast energy (depending on the depth of the mine and the configuration of the blast) is directed with a lateral component. The greater the ground clearance of the vehicle, the greater probability that a portion of the blast traveling laterally will not encounter the vehicle. Even if some of the debris and blast moving laterally encounter portions of the bottom of the vehicle they are traveling at a small angle to the surface of the bottom. Thus, the energy and debris is more likely to deflect from the surfaces that they encounter rather than transfer its energy to them.
Moreover, if the bottom of the vehicle is flat and parallel to the ground, much of the energy of the mine and any material propelled by it hits the bottom surface perpendicular to its surface. As a result the energy of the material and the blast is most efficiently transferred to that surface and the probability that the armor bottom will be defeated and breached is maximized.
In order to produce maximum probability that a mine will breach the armor of a vehicle, the blast may be designed to be focused and directed in a specific direction. Normally an anti-vehicle mine directs its blast in an upward-projecting cone, with the apex of the cone in the ground, and the base of the cone striking the vehicle. This is accomplished by shaping the explosive charge, providing a directed cavity to direct the initial blast, and the inherent guidance of the blast resulting from the mine being surrounded on all but the top surface with the mass of the earth in which it is buried. As such, a normal blast will propel gas and solid material over the mine in a cone describing an angle of approximately 60°. If, however, the mine detonates directly underneath the wheel or track of a vehicle, more of the blast energy is deflected laterally.
In irregular or guerilla warfare, explosive devices often are fabricated from any available explosive materials and may not have the trigger mechanisms of manufactured anti-vehicle mines. These irregular devices are commonly referred to as “roadside bombs” or “improvised explosive devices” or “IEDs.” It may not be practicable to take the time to bury such devices in the anticipated path of vehicles to be attacked. Such devices are many times simply disguised and placed adjacent the path of the vehicle. They are then detonated when the target vehicle is adjacent the device. As a result, the blast and material propelled by it tend to impinge laterally on the side of the target vehicle.
If the side of the target vehicle adjacent the exploding device is flat, much of the energy of the blast and any material propelled by it hits the side surface perpendicularly. As a result, the energy of the material and the blast energy is efficiently transferred to the surface, and the probability that armor on the sides of the vehicle will be defeated and breached is increased.
While any practical mine or improvised explosive device can be defeated by armor of sufficient strength and thickness, the extra armor is heavy and expensive, adds weight to the vehicle which, in turn places greater strain on the vehicle engine, and drive train.
Thus, there exists a need for an armored vehicle that can survive detonation of anti-vehicle mines and improvised explosive devices without requiring excess thicknesses of armor. Preferably, such armor would be made of material that can be readily fabricated and incorporated into the vehicle design at a reasonable cost.